The binding and printing industries often rely on high-speed sheet material handling systems for printing, collating, binding, and otherwise handling sheet material, for example, sheets of paper. This sheet material, for example, individual sheets, newspapers, magazines, inserts and “onserts” (that is, sheet material used when collating newspapers), books, brochures, and the like, is typically, fed to and accumulated in containers or “magazines” or “hoppers” and withdrawn from the magazines or hoppers for further processing. One particular sheet material that is handled in the binding and printing industry is what is known in the art as a “signature”. A signature typically comprises two or more sheets of paper that may be folded to form a spine, that is a “spine fold”. Signatures may contain four or more pages of text or graphics, for example, 30 or more pages of text or graphics.
In the manufacture of books, it is common to assemble the book on a collecting conveyor by sequentially withdrawing signatures from magazines, or hoppers, containing stacks of signatures. In producing a book, typically, a plurality of serially-arranged hoppers, separating devices, and feeders are employed for gathering and collating the printed sheets of, for example, signatures. Typically, the separating devices separate and withdraw the sheet material from the hoppers and feed the sheet material to a rotating drum. The rotating drum then feeds the sheet material to a conveyor that collects and transfers the separated printed sheets for collation, binding, or other handling. The separation of the sheet material from the stacked sheet material is typically effected by a rotating disk separator. The separation of the sheet material by the disk separator is typically aided by a suction device, for example, a device known in the art as a “sucker”. One typical disk-type separator is disclosed in U.S. Pat. No. 6,193,229 B1, the disclosure of which is incorporated by reference herein in its entirety. The disk separator separates and feeds the sheet material to a rotating drum that accepts and retains the sheet material and conveys it to the conveyor. The disk separator, typically with the aid of the suction device, deflects the edge of the lower-most article of sheet material in the hopper stack. When the sheets to be withdrawn from the hopper are in the form of signatures, the deflected edge is typically the spine fold portion of the signature. The rotating drum positioned below the disk separator typically includes some means of retaining the sheet material as it rotates, for example, devices known in the art as “grippers”. The conveyor that receives the sheet material is typically a horizontal conveyor. This horizontal conveyor may also receive sheet material from other, typically serially-positioned, feeding drums. A common drive mechanism typically drives and synchronizes the operation of the separator, suckers, feed drum, grippers, and the conveyer.
The throughput of such systems is dependent upon on how closely together the sheet material is spaced, and on how fast the sheet material is moved. Accordingly, the throughput of such systems may be optimized by spacing the sheet material as closely together as possible and by maximizing the speed of operation of each of the components. One important factor in the operation of disk-type separators is the alignment of the sheet material with the separator disk. Since the disk separators of such devices rotate at high speed and typically “bite into” the stack of sheet material in the hopper, misalignment of the sheet material and the disk can cause misfeeds, jamming, or even damage to the equipment.
According to prior art methods, sheet material typically fed to the hopper that feeds the disk separate by means of some form of conveyor. Typically, the conveyor feeds the sheet material to the hopper such that the sheet material forms a uniform stack in the hopper. Forming a uniform stack of sheet material in the hopper helps to ensure that the sheet material is uniformly stacked so that the sheet material can be engaged and separated by the rotating disk separator. The formation of a non-uniform or misaligned stack of sheet material in the hopper can interfere with the uniform separation of the sheet material by the disk separator and, in the worst case, cause jamming of the sheet material and disruption of the production facility. Thus, the uniform alignment of the stacked sheet material is highly desired by the operator.
In prior art sheet material handling systems, the uniform alignment of the sheet material is aided by a device known in the art as a “backguide”. A backguide is a device located beneath the point at which the conveyor introduces sheet material to the hopper and acts as a guide or baffle which promotes the proper alignment of the sheet material as the sheet material is stacked into the hopper. Among other things, the backguide minimizes the misalignment of the stack of sheet material by providing a surface upon which the sheet material can bear as the sheet material is inserted into the hopper.
In the conventional art, the hopper typically comprises a platen or “hopper tray” upon which the sheet material is stacked. The hopper tray is typically an adjustable tray that permits the operator to vary the tray's position and orientation depending upon the nature of the sheet material being handled by the hopper. For example, stiffer sheet materials typically require a different tray position and orientation relative to the feeding mechanism than do less stiff, or flimsier, sheet materials. Proper location of the tray promotes optimum feeding of the sheet material to the disk separator. The lateral position of the hopper tray typically can be varied by moving, or translating, the tray either toward the disk separator, that is, in the “fore” direction, or away from the disk separator, that is, in the “aft” direction. The hopper tray may also be tilted, or rotated, in the fore and aft directions depending upon the stiffness of the sheet material being handled.
This translation or rotation of the hopper tray typically influences the operation of the backguide. Since the backguide typically and preferably works in unison with the hopper tray, conventional backguides are typically rigidly attached to the hopper tray so that the backguide translates or rotates with the translation or rotation of the hopper tray. However, rigidly mounting the backguide to the hopper tray whereby the backguide moves with the hopper tray can interfere with the function of the backguide and cause misalignment of the sheet material. One aspect of the present invention overcomes this disadvantage of the prior art.
In one prior art configuration, the backguide comprises a two-piece backguide, one piece fixed to the hopper tray and one piece fixed to the conveyor housing feeding the hopper tray. However, translation and rotation of one piece of the two-piece backguide with the hopper tray relative to the fixed backguide can produce misalignment between the two pieces and can cause jamming of the sheet material, which of course is to be avoided. One aspect of the present invention overcomes this disadvantage of the prior art backguides.